1. Technical Field
The present invention relates to a kit effectively used for easily determining or judging on whether a specific immunostimulant polysaccharide is effective, or not, for a specific subject as an immunostimulant agent and a method for estimating the efficiency of a candidate material as an immunostimulant agent.
2. Background of the Invention
It has commonly been known that the immunostimulant polysaccharides such as β-glucans represented by lentinan are effective as immunostimulant agents and/or anti-pernicious tumor agents, but it has likewise been known that the development of their effect would greatly be affected by the variations between individuals (Non-Patent Document No. 1 specified later).
On the other hand, it has been known that the immunostimulant polysaccharides are bonded to the mononuclear cells such as monocytes, granulocytes and lymphocytes, which are present in the peripheral blood of the mammals such as human beings and mice, on the surface of these mononuclear cells (Non-Patent Document Nos. 2 and 3 specified later). Moreover, it has also been proved that the ability of the immunostimulant polysaccharide to bind to mononuclear cells present in the peripheral blood would variously be affected by the differences between individuals or the differences between mouse strains and accordingly, there would be a high possibility such that the binding ability of the immunostimulant polysaccharide may correlate with the development of the foregoing effects of the polysaccharide.
As means for estimating or determining the ability of the immunostimulant polysaccharide to bind to mononuclear cells present in the peripheral blood (peripheral blood mononuclear cell(s)), there has been known, for instance, a method which makes use of an antibody against an immunostimulant polysaccharide such as anti-lentinan antibody. However, this method suffers from various problems in that it is difficult to use such an anti-lentinan antibody in this method since the antibody is an IgM and that the anti-lentinan antibody is a self-productive antibody and accordingly, it would be quite difficult to constantly supply such an antibody having a uniform titer. In addition, the method further suffers from a problem such that the method requires the use of complicated operations since the method requires the step of separating the white blood cells fraction from the blood and the subsequent step for subjecting the antibody to a reaction in the presence of the blood serum.
Contrary to this, there has also been known a method in which a fluorescence-labeled immunostimulant polysaccharide is added to peripheral blood mononuclear cells (whole blood), followed by cultivating the same and the subsequent determination of the fluorescent intensity emitted therefrom (see Non-Patent Document Nos. 4 and 5).
This method is one which permits the considerably efficient and highly precise determination of the ability of a labeled immunostimulant polysaccharide to bind to peripheral blood mononuclear cells as compared with the foregoing method which makes use of, for instance, an anti-lentinan antibody. As a result of the examinations carried out by the inventors of this invention, however, the values measured by the method each include not only the linkages specific to or peculiar to the immunostimulant polysaccharide, but also the linkages non-specific thereto. Accordingly, even if the method provides a positive result, the positive value does not always correspond to only the binding ability specific to the immunostimulant polysaccharide derived from a subject to be examined and therefore, it has been proved that the binding ability of the subject examined may not necessarily correlate with the desired effect.
Non-Patent Document No. 1: Cancer Res., 1984, 44:5132;
Non-Patent Document No. 2: 50th Annual Mtg. Proc. Jpn. Cancer Assoc., p. 259 (1991);
Non-Patent Document No. 3: Int. J. Immunopharmac., 1996, 18:211;
Non-Patent Document No. 4: J. Clin. Invest., Vol. 98, No. 1, July 1996, pp. 50-61;
Non-Patent Document No. 5: J. Exp. Med., Vol. 196, No. 3, Aug. 5, 2002, pp. 407-412.